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Biomedical subjects

E G MacEwen

Publications and source records attributed to E G MacEwen.

At least 19 recordsLinked to original sources
PubMed1992

Idiopathic granulomatous disease with ocular adnexal and cutaneous involvement in a dog.

Idiopathic granulomatous disease was the cause of bilateral eyelid masses and additional ocular adnexal disease in a dog. Histologically similar granulomas developed concurrently in distant sites including the limbs, prepuce, and testicles. Periodic resolution and redevelopment of the masses were observed and were unaffected by corticosteroid treatments. Rapid diminution of some of the masses was found after treatment with polyethylene glycol modified L-asparaginase, but poor client compliance and episodes of spontaneous resolution of some of the masses made it difficult to accurately assess effectiveness of treatment. Clinicians should be aware that ocular adnexal granulomas may simulate neoplasms and be a component of a more widespread disease process.

Animals↗
PubMed1992

Effect of colony-stimulating factors on number and function of circulating monocytes in normal dogs.

Recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) and recombinant canine granulocyte colony-stimulating factor (rcG-CSF) were administered to normal dogs, and effect on monocyte number and function was evaluated. rhuGM-CSF, administered for 14 days, induced a 2.5-fold increase in monocyte counts on day 3. Leukocytes increased two-fold after 1 day. Counts peaked on day 11, then declined, approaching pretreatment counts by day 15. On day 7, in vivo monocyte cytostasis activity was significantly enhanced, and declined on day 14. rcG-CSF induced a 4.5-fold increase in monocyte counts on day 3. Leukocyte counts increased three-fold after 1 day. Increased counts were maintained for 69 days, at which time treatment was discontinued. There was no effect of rcG-CSF on in vivo monocyte cytostasis activity on days 7 and 14.

Animals↗
PubMed1991

Obesity in the dog: role of the adrenal steroid dehydroepiandrosterone (DHEA).

It is estimated that 25-50% of pet dogs are overweight. In rodents and humans the adrenal steroid dehydroepiandrosterone (DHEA) has been associated with loss of body weight and reduction in total body fat content. We have shown that administration of DHEA results in weight loss in spontaneously obese dogs. DHEA also lowered serum cholesterol, in particular, the low density lipoprotein component of the plasma cholesterol. We hypothesize that treatment of obese dogs with DHEA in combination with a low energy, high fiber diet will result in greater weight loss when compared with dogs on the same diet, without DHEA. In the current study, spontaneously obese dogs were fed a uniform low energy, high fiber diet and then randomized to receive DHEA or placebo. Preliminary results show that the mean total body weight lost for dogs receiving DHEA was 3.59 kg compared with 2.38 kg for dogs receiving placebo (P greater than 0.05). The percent excess body weight (above ideal body weight) lost for the DHEA group was 65.7 versus 31.4 for the placebo group (P less than 0.02). The percent excess body weight lost per month on the study for the DHEA group was 15 versus 8.2 for the placebo group (P = 0.069). Although these results are preliminary, they indicate that DHEA combined with a low energy, high fiber diet enhances the loss of excess body weight compared with diet modification alone.

Animals↗
PubMed1990

Spontaneous tumors in dogs and cats: models for the study of cancer biology and treatment.

Spontaneous tumors in dogs and cats are appropriate and valid model tumor systems available for testing cancer therapeutic agents or studying cancer biology. The pet population is a vastly underutilized resource of animals available for study. Dogs and cats develop spontaneous tumors with histopathologic and biologic behavior similar to tumors that occur in humans. The tumors with potential relevance for human cancer biology include osteosarcoma, mammary carcinoma, oral melanoma, oral squamous cell carcinoma, nasal tumors, lung carcinoma, soft tissue sarcomas, and malignant non-Hodgkin's lymphoma. Canine osteosarcoma is a malignant aggressive bone tumor with a 90% metastasis rate after surgical amputation. Its predictable metastatic rate and pattern and its relative resistance to chemotherapy make this tumor particularly attractive for studying anti-metastasis approaches. Canine and feline malignant mammary tumors are fairly common in middle-aged animals and have a metastatic pattern similar to that in women; that is, primarily to regional lymph nodes and lungs. Chemotherapy has been minimally effective, and these tumors may be better models for testing biological response modifiers. Oral tumors, especially melanomas, are the most common canine malignant tumor in the oral cavity. Metastasis is frequent, and the response to chemotherapy and radiation has been disappointing. This tumor can be treated with anti-metastatic approaches or biological response modifiers. Squamous cell carcinomas, especially in the gum, are excellent models for radiation therapy studies. Nasal carcinomas are commonly treated with radiation therapy. They tend to metastasize slowly, but have a high local recurrence rate. This tumor is suitable for studying radiation therapy approaches. Primary lung tumors and soft tissue sarcomas are excellent models for studying combined modality therapy such as surgery with chemotherapy or biological response modifiers. Finally, non-Hodgkin's lymphoma is a common neoplastic process seen in the dog. These tumors respond to combination chemotherapy and have great potential as a model for newer chemotherapeutic agents and biological response modifiers. This paper will further elaborate on the relative merits of each tumor type as a model for human cancer therapy and biology.

Animals↗
PubMed1990

Biologic response modifiers: the future of cancer therapy?

The major shift today has been away from nonspecific compounds acting on immune mechanisms to using biologics which have specific, defined roles in acting on the immune response. The field of biologic response modification is progressing very rapidly. New peptides are being identified, as are receptors for these peptides, autocrines, lymphokines, cytokines, growth factors, differentiation factors, hormones, and so on-all of which will control body function, cell populations, and cell to cell interactions. This rapidly advancing area of research in cancer biology and cancer therapy may hold the key to the future of successful therapy.

Animals↗
PubMed1990

Quantitative morphologic study of the pituitary and thyroid glands of dogs administered L-thyroxine.

To determine the effects of long-term thyroxine treatment, histomorphometric analysis was performed on the pituitary and thyroid glands of healthy dogs, dogs treated for 9 weeks with a replacement dose of L-thyroxine, and dogs at 6 weeks after cessation of thyroxine treatment. In treated dogs, the volume density of thyrotropes decreased during thyroxine treatment and increased 6 weeks after cessation of treatment, compared with thyrotropes of healthy nontreated dogs. The activity of the thyroid gland was decreased in dogs during thyroxine treatment, as evidenced by decreases in epithelial volume density, epithelial height, and follicular area, and increase in colloid volume density, compared with thyroid gland activity in nontreated dogs. After cessation of thyroxine treatment, the thyroid gland had decreased colloid area, follicular area, and epithelial volume density, and increased interstitial volume density, compared with the thyroid gland of healthy nontreated dogs. Thyroxine treatment resulted in suppression of pituitary thyrotropes and thyroid follicular activity.

Animals↗
PubMed1990

Thyroid function tests in euthyroid dogs treated with L-thyroxine.

The effects of treatment with L-thyroxine (1 mg/m2 of body surface/d, PO, for 8 weeks) on the thyroxine (T4) and triiodothyronine (T3) responses to thyrotropin (TSH) and thyrotropin-releasing hormone (TRH) administration were determined in 10 euthyroid Beagles; 4 other dogs acted as controls. The TSH response test was performed before treatment and at weeks 2, 4, and 8 of treatment in all dogs and at 2 and 4 weeks after cessation of treatment in 6 dogs. The TRH response test was performed before treatment and at week 6 of treatment in all dogs and at 5 weeks after cessation of treatment in 6 dogs. Suppression of the T3 response to TSH was evident at treatment week 2, whereas the T4 response was suppressed at week 4 and remained suppressed for the duration of the study. Four weeks after stopping treatment, T4 and T3 responses to TSH in 2 dogs were within the hypothyroid range. The T4 response to TRH was completely suppressed after 6 weeks of thyroxine treatment, but returned to pretreatment values by 5 weeks after cessation of treatment. Suppression of thyroid and pituitary function is evident after administration of a replacement dose of L-thyroxine to euthyroid dogs.

Animals↗
PubMed1990

Reduction in body weight and cholesterol in spontaneously obese dogs by dehydroepiandrosterone.

We studied the effect(s) of exogenous dehydroepiandrosterone (DHEA) in spontaneously obese dogs. Nineteen euthyroid obese and six non-obese normal dogs were evaluated. Dogs received DHEA for three months at an escalating dose of 30-75 mg/kg p.o. daily. We found a 3 percent reduction in total body weight/month in 68 percent of the obese dogs, without reduction in food intake. The normal dogs did not lose weight or reduce food intake. Serum cholesterol in obese dogs went from 226 to 173 mg/dl post-treatment and in normal dogs from 128 to 89 mg/dl. Analysis of lipoproteins in four normal dogs revealed that the marked reduction in cholesterol most significantly affected the LDL-HDL1 fraction.

Animals↗
PubMed1989

Therapy for osteosarcoma in dogs with intravenous injection of liposome-encapsulated muramyl tripeptide.

Canine osteosarcoma is a spontaneous malignancy in dogs, characterized by micrometastasis to pulmonary and extrapulmonary tissues at the time of diagnosis. Standard treatment involves amputation of the affected leg, but median survival time is 3-4 months with death due to metastasis. A randomized double-blind trial was conducted to evaluate liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (liposome/MTP-PE) as a treatment for metastasis in dogs undergoing amputation for osteosarcoma. Fourteen dogs were treated with liposome/MTP-PE, and 13 were treated with empty liposomes. Median survival time was 222 days for dogs treated with liposome/MTP-PE, compared to 77 days for dogs treated with empty liposomes (P less than .002). In the liposome/MTP-PE-treated group there were still four dogs alive and free of metastasis at greater than 1 year post surgery. Treatment was well tolerated; no significant toxic effects were noted except for mild elevations in body temperature (1-2 degrees C) for 2-6 hours post injection.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Treatment and prognostic factors in lymphoma in cats: 103 cases (1977-1981).

The records of 103 cats with lymphoma that underwent chemotherapy were reviewed. Diagnosis was confirmed by cytologic or histopathologic examination of appropriate tissue specimens. Sixty-four cats (62%) had a complete response to chemotherapy (median survival time, 7 months); 21 cats (20%) had a partial response (median survival time, 2.5 months); and 18 cats had a minimal response (median survival time, 1.5 months). Seventy-seven cats (75%) died of recurrent or progressive lymphoma, 9 cats died of feline leukemia-related anemia, 13 cats died of unrelated causes, and 4 cats were alive. Stage of disease was significantly (P = 0.009) related to response to treatment, and stage of disease and FeLV status were both significantly (P = 0.002 and P less than 0.001, respectively) related to survival.

Animals↗
PubMed1987

Renal lymphoma in cats: 28 cases (1977-1984).

Renal lymphoma was diagnosed, staged, and treated in 28 cats. Renal lymphoma staging was done according to clinical findings: 11 cats had stage-2 lymphomas, 5 had stage-3 lymphomas, 6 had stage-4 lymphomas, and 6 had stage-5 lymphomas. All cats were treated with chemotherapy: 17 cats had a complete response, 9 cats had a partial response, and 2 cats had no response. The cats with stage-2 lymphomas that were FeLV-test negative had the best response to treatment.

Animals↗
PubMed1987

A preliminary study on the evaluation of asparaginase. Polyethylene glycol conjugate against canine malignant lymphoma.

Thirty-seven dogs with malignant lymphoma were treated with either polyethylene glycol conjugated (PEG) asparaginase alone (10-30 IU/kg intraperitoneally [IP] weekly--20 dogs) or PEG-asparaginase combined with one cycle of chemotherapy (vincristine, cyclophosphamide, methotrexate, and prednisone), followed by maintenance PEG-asparaginase (30 IU/kg, IP weekly--17 dogs). In the 20 dogs (eight were chemotherapy resistant) treated with PEG-asparaginase alone, seven had a complete response (CR), seven had a partial response (PR), five had no response (NR), and one was not evaluable (NE). The duration of response (CR + PR) ranged from 14 to 102 days (median, 48 days). In the eight chemotherapy-resistant dogs (seven were previously resistant to L-asparaginase) four had responses (one CR and three PR). In the 17 dogs treated with combined PEG-asparaginase and chemotherapy, 13 had a CR, two had a PR, and two had NR. None of the dogs had had prior chemotherapy, and the duration of response (CR + PR) ranged from 7 to 840+ days, with a median of 126+ days. Four dogs are still on maintenance PEG-asparaginase at 16+, 21+, 26+, and 28+ months. Toxicity consisted of death due to massive tumor breakdown (two dogs), disseminated intravascular coagulation (DIC--one dog), hypersensitivity reaction (one dog), vomiting (three dogs) and soft stools (three dogs). Four normal dogs were given very high doses of PEG-asparaginase (200 IU/kg and 1200 IU/kg) once weekly for two treatments without any significant toxicity. These results indicate that PEG-asparaginase has antitumor activity in dog with spontaneously occurring malignant lymphoma.

Animals↗
PubMed1987

Generalized lymphadenopathy resembling lymphoma in cats: six cases (1972-1976).

Six cases of prominent generalized peripheral lymphadenopathy in the cat were reviewed. The lymph node biopsy specimens of these cats had many histologic features of lymphoma. One cat was euthanatized after the initial diagnosis of lymphoma. In the other 5 cats, the lymphadenopathy regressed without therapy within 1 to 17 weeks.

Animals↗
PubMed1987

Evaluation of some prognostic factors for advanced multicentric lymphosarcoma in the dog: 147 cases (1978-1981).

A total of 147 dogs treated with a combination of chemotherapy procedure (vincristine, L-asparaginase, cyclophosphamide, and methotrexate) were evaluated for response to therapy and the influence of age, sex, clinical stage, and body weight to duration of response. Complete response was achieved in 113 dogs (77%), partial response in 26 dogs (17.7%), and no response in 8 dogs (5.4%). The median survival time for the dogs with complete and partial responses was 265 days. An analysis of factors associated with prognosis revealed that age, clinical stage, and body weight were not associated with response to therapy, whereas sex was. Females had a significantly prolonged remission and survival time (P = 0.0001).

Age Factors↗
PubMed1986

Prognostic factors for multiple myeloma in the dog.

Multiple myeloma was diagnosed in 60 dogs. Diagnosis was confirmed in each case by observation of greater than 5% plasma cells on examination of a bone marrow aspirate and detection of monoclonal gammopathy of immunoglobulin (Ig) A or IgG. Treatment with melphalan, cyclophosphamide, and prednisone was associated with long-term survival (median, 540 days). Response to therapy was significantly related to prognosis (P less than 0.01), whereas hypercalcemia and Ig light chain proteinuria (Bence Jones) were associated with shorter median survival times.

Animals↗
PubMed1986

A clinicopathologic and ultrastructural study of undifferentiated malignant tumors of the oral cavity in dogs.

Undifferentiated malignant tumors of the oral cavity were diagnosed in six dogs under 2 years of age. The dogs were examined because of pain and swelling of the upper molar or premolar areas. In all six dogs, the tumors were initially misdiagnosed as infections or carnasal abscesses. The differential diagnosis included malignant lymphoma, osteosarcoma, mesenchymal chondrosarcoma, embryonal rhabdomyosarcoma, and malignant melanoma. Electron microscopy of three neoplasms showed that there were no specific features characteristic of carcinoma or sarcoma. Immunoperoxidase studies for cytokeratins, epithelial membrane antigen, actin, myosin, desmin, and vimentin were also negative. We conclude that these tumors be designated undifferentiated malignant tumors of the oral cavity until histogenesis is established.

Animals↗